Gary Lewis contacted a female on an adult dating site without realising it was a fake profile which had been set up. The decoy then told him she was actually only 13 but he carried on the conversation.
Lewis broke off the sex chats for a while but resumed them on his birthday just before Christmas last year
He went on to suggest that the decoy, who was using the false identity of a girl called Charlotte, should perform a sex act on herself.
It led to him being confronted in the street by a group of paedophile hunters who spent 40 minutes questioning him while screening the footage live to their supporters. The police were called and he was arrested
Lewis, aged 48, of Manor Road, Camborne, denied attempting to inciting a child to sexual activity and attempted sexual communications with a child but was found guilty by a jury at Truro Crown Court last month.
He was jailed for three years by Judge Simon Carr, sitting at Exeter Crown Court, and ordered to sign on the sex offenders register for life.
He was also made subject of a Sexual Harm Prevention Order which will allow the police to monitor his online activity after his release.